Design And Performance Of Gallium Oxidesolar Blind Detector Based On Heterostructure

Solar blind ultraviolet photodetector has important practical application value in the fields of military and civilian,such as missile tracking,secure communication,and environmental monitoring,etc.Ga2O3 is a wide band gap semiconductor material with direct band gap.Owing to suitable band gap,ultrahigh breakdown field strength and stable physical and chemical properties,Ga2O3 is one of the ideal candidate materials for solar blind photodetectors.The Ga2O3-based solar blind photodetectors show great potential in the field of solar blind detection due to their many advantages,such as low dark current,small size,and filterfree,etc.However,the reported Ga2O3-based solar-blind photodetectors have fundamental problems such as low sensitivity,slow response speed,abundant interface defects caused by lattice mismatch,difficult p-type doping and poor heteroepitaxy interface.Facing with the important scientific problems existing in the current Ga2O3 solar blind detectors,this work focuses on the preparation of Ga2O3 epitaxial thin films and the design of Ga2O3-based heterostructure.The main contents as follow:1.The effect of growth parameters on the epitaxial films was systematically studied,and the law of changeable bandgap of films was revealed.Then,taking a simple photoconductive-type photodetector based on Ga2O3 thin film as an example,the regulation mechanism of internal factors such as growth temperature,oxygen partial pressure,and external factors such as incident light intensity and bias voltage on the photoelectric behavior of Ga2O3-based solar blind detector is analyzed and summarized,which provides a fundamental material and theory for the next work.2.Facing with the low response in the Ga2O3-based solar blind photodetector,an avalanche photodetector with amorphous Ga2O3/ITO heterostructure was designed.By applied an appropriate reverse voltage on the heterojunction,the avalanche multiplication mode is activated.The ultrahigh avalanche gain(6.8×104)is achieved,which significantly improves responsivity of the device.The responsivity is as high as 5.9×104 A/W.The prepared device with mild processing temperature and superior performance provides potential possibilities for the practical application based on Ga2O3 material.3.Owing to the problem of large lattice mismatch and p-type doping,the van der Waals heterojunction based on Ga2O3 is proposed and fabricated.The two-dimensional material with layered structure is introduced into the Ga2O3-based photodetector.Two-dimensional material has no dangling bond on the surface,and combined only through weak van der Waals force in the interface,which avoids lattice mismatch during the heteroepitaxy and improves effectively the interface quality of the heterostructure.The prepared GaSe/Ga2O3 van der Waals pn heterojunction solar blind photodetector demonstrations a responsivity is up to 51.9 A/W and obvious photovoltaic characteristics.The graphene/amorphous Ga2O3 van der Waals heterojunction has high responsivity with 22.7 A/W and excellent bending stability.It shows a great potential in the preparation of flexible wearable solar blind photodetectors with high sensitivity.4.Based on the excellent photoelectric properties of heterostructures,a novel phase junction-type Ga2O3 solar blind photodetector was designed.Because of the strong built-in electric field at the crystalline/amorphous interface,the responsivity of the device is achieved to 0.81 A/W,the photodark-current-ratio reaches 107,and the response time is as low as 12 ns.The results display a novel phase junction with the high performance,also provide a new routine for the other optoelectronic devices.